The invention uses a molten salt composed of two metals. Under electrolysis, the salt separates into the metal components — one of which is lighter than the salt and floats to the top, the other being denser and sinks to the bottom.

Put energy in and the salt separates — the metal layers get thicker and the salt layer gets thinner. Reverse the process to take energy out — salt is formed and the metal layers get thinner.

Supposedly more power density than lithium batteries, and a good match for installing at fixed locations, such as the base of windmills."

This seems like a worthy competitor to flow batteries and other bulk energy storage.

Comparing it to a flow battery [wikimedia.org] (which is a battery where the electrolyte flows from storage to the the reaction area instead of having to stay in one place) it seems like this technology neatly solves one limitation. Flow batteries have energy producing components and electrolyte storage and they scale independently (get more electrolyte to extend runtime, get more reaction units to up capacity) but this neatly combines them